Bottom Line:
Insulin-like-factor-binding-protein 3 (IGFBP-3) is known to modulate the activity of insulin-like growth factors (IGFs) besides having a number of IGF-independent effects on cell growth and survival.In the present work, we have evaluated the levels of IGFBP-3 in the blood serum and tissues of patients affected by cutaneous melanoma, showing that loss of IGFBP-3 from both is strongly correlated with disease progression and reduced survival.In summary, IGFBP-3 appears to exert a specific inhibitory effect on melanoma growth and dissemination, suggesting that it may qualify as a useful therapeutic agent in melanomas and perhaps other cancers, at the least as a valid adjuvant therapy during treatment with conventional anti-tumoral drugs.

ABSTRACTInsulin-like-factor-binding-protein 3 (IGFBP-3) is known to modulate the activity of insulin-like growth factors (IGFs) besides having a number of IGF-independent effects on cell growth and survival. IGFBP-3 has been reported to decrease significantly in the blood serum of patients affected by certain cancers. In the present work, we have evaluated the levels of IGFBP-3 in the blood serum and tissues of patients affected by cutaneous melanoma, showing that loss of IGFBP-3 from both is strongly correlated with disease progression and reduced survival. In vitro treatment with IGFBP-3 of human and murine metastatic melanoma cell lines specifically inhibited the cells' migratory and invasive behaviour, inducing up-regulation of melanocytic differentiation markers such as tyrosinase activity and melanin content. A molecular analysis of the cellular pathways transducing the effect of IGFBP-3 implicated the Akt-GSK3β axis. Moreover, administration of IGFBP-3 in vivo to SCID mice inoculated with human metastatic melanoma cells strongly reduced or completely inhibited tumor growth. In summary, IGFBP-3 appears to exert a specific inhibitory effect on melanoma growth and dissemination, suggesting that it may qualify as a useful therapeutic agent in melanomas and perhaps other cancers, at the least as a valid adjuvant therapy during treatment with conventional anti-tumoral drugs.

pone-0098641-g006: IGFBP-3 acts independently of IGF-1.A) Western blot analysis for the detection of IGF-1 in lysates or culture media (CM) of Me501 cells. IGF-1 rec represents the positive control with recombinant IGF-1 (5 ng). B) Western blot analysis for detection of Tyr 1135-phosphorylation on the IGF-1 receptor β. Me501 cells were grown for 24 h in the presence of 10% serum (left panels) or in the absence of serum (right panels). For each group, treatments with IGFBP-3 or with anti-IGF-1 antibodies were performed. The amount of phosphorylated IGF-1-β receptor was quantified by densitometric analysis using total receptor (which remained unchanged) as the internal standard. C) Scratch-repair capacity of Me501 cells in the presence of anti-IGF1-antibodies and of IGFBP-3. The images shown are representative of experiments that were repeated at least three times.

Mentions:
Firstly, migration and invasion assays were performed in the absence of serum and hence in the absence of IGFs. The possibility that the cells themselves produced IGF-1 was discounted on the basis of western blot analysis of both cell lysates and culture media (Fig. 6A). IGF-1 mediated effects were further excluded by determining the state of activation of the IGF-1 receptor (IGF-1R).

pone-0098641-g006: IGFBP-3 acts independently of IGF-1.A) Western blot analysis for the detection of IGF-1 in lysates or culture media (CM) of Me501 cells. IGF-1 rec represents the positive control with recombinant IGF-1 (5 ng). B) Western blot analysis for detection of Tyr 1135-phosphorylation on the IGF-1 receptor β. Me501 cells were grown for 24 h in the presence of 10% serum (left panels) or in the absence of serum (right panels). For each group, treatments with IGFBP-3 or with anti-IGF-1 antibodies were performed. The amount of phosphorylated IGF-1-β receptor was quantified by densitometric analysis using total receptor (which remained unchanged) as the internal standard. C) Scratch-repair capacity of Me501 cells in the presence of anti-IGF1-antibodies and of IGFBP-3. The images shown are representative of experiments that were repeated at least three times.

Mentions:
Firstly, migration and invasion assays were performed in the absence of serum and hence in the absence of IGFs. The possibility that the cells themselves produced IGF-1 was discounted on the basis of western blot analysis of both cell lysates and culture media (Fig. 6A). IGF-1 mediated effects were further excluded by determining the state of activation of the IGF-1 receptor (IGF-1R).

Bottom Line:
Insulin-like-factor-binding-protein 3 (IGFBP-3) is known to modulate the activity of insulin-like growth factors (IGFs) besides having a number of IGF-independent effects on cell growth and survival.In the present work, we have evaluated the levels of IGFBP-3 in the blood serum and tissues of patients affected by cutaneous melanoma, showing that loss of IGFBP-3 from both is strongly correlated with disease progression and reduced survival.In summary, IGFBP-3 appears to exert a specific inhibitory effect on melanoma growth and dissemination, suggesting that it may qualify as a useful therapeutic agent in melanomas and perhaps other cancers, at the least as a valid adjuvant therapy during treatment with conventional anti-tumoral drugs.

ABSTRACTInsulin-like-factor-binding-protein 3 (IGFBP-3) is known to modulate the activity of insulin-like growth factors (IGFs) besides having a number of IGF-independent effects on cell growth and survival. IGFBP-3 has been reported to decrease significantly in the blood serum of patients affected by certain cancers. In the present work, we have evaluated the levels of IGFBP-3 in the blood serum and tissues of patients affected by cutaneous melanoma, showing that loss of IGFBP-3 from both is strongly correlated with disease progression and reduced survival. In vitro treatment with IGFBP-3 of human and murine metastatic melanoma cell lines specifically inhibited the cells' migratory and invasive behaviour, inducing up-regulation of melanocytic differentiation markers such as tyrosinase activity and melanin content. A molecular analysis of the cellular pathways transducing the effect of IGFBP-3 implicated the Akt-GSK3β axis. Moreover, administration of IGFBP-3 in vivo to SCID mice inoculated with human metastatic melanoma cells strongly reduced or completely inhibited tumor growth. In summary, IGFBP-3 appears to exert a specific inhibitory effect on melanoma growth and dissemination, suggesting that it may qualify as a useful therapeutic agent in melanomas and perhaps other cancers, at the least as a valid adjuvant therapy during treatment with conventional anti-tumoral drugs.